It has been reported that Tesla threatened to stop working with a law firm if it didn’t fire one of its attorneys who previously worked at the Securities and Exchange Commission (SEC) during a probe of its CEO, Elon Musk, which resulted in a $20 million fine and Musk stepping down as chariman of the automaker.

The Wall Street Journal reports that a partner at law firm Cooley LLP received a call from one of Elon Musk’s lawyers making the ultimatum. The former SEC lawyer had been hired by Cooley for its securities litigation and enforcement practice after he had previously interviewed Musk during the SEC’s investigation about the billionaire’s claims of having secured funding to take Tesla private in 2018.

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Cooley LLP was representing Tesla in a number of lawsuits and when the law firm declined to fire the attorney, the car manufacturer begun taking steps to replace Cooley or add additional counsel in various suits. In addition, SpaceX has stopped using Cooley for regulatory work, The Wall Street Journal adds.

Interestingly, Tesla’s managing counsel David Misler was once an attorney for the Securities and Exchange Commission.

This is far from the only time that Elon Musk has clashed with regulators. Last year, Duke University professor and automated systems expert Missy Cummings was named as an advisor to the NHTSA in its investigation of Tesla’s Autopilot system. Cummings had been critical of the system in the past and Musk swiftly took to Twitter to tell his millions of followers that “her track record is extremely biased against Tesla.”

Cummings quickly became the focus on attacks from many of Musk’s followers and the NHTSA later required the professor to recuse herself from any Tesla-specific matters.